ABB REX 521, Technical Reference Manual, General

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1MRS 751108-MUM Protection Relay
Technical Reference Manual, General
REX 521
Even a total breakdown of the relay, e.g. on loss of power supply, will be detected
as the IRF relay operates in a fail-safe mode, causing a signal when the relay drops
off. The serial communication will also indicate loss of contact to the module. When
the relay is in the IRF state, it tries to recover by resetting every five minutes.
As long as the fault remains, the relay continues to perform internal tests. Should the
fault prove to be of temporary nature, normal operation is recovered after reset and
an event “IRF reset” (E30) is sent over the serial communication.
4.1.11.1. Fault indication
The self-supervision signal output operates on the closed circuit principle. Under
normal conditions the output relay is energized and the contact gap 3-5 is closed.
Should the auxiliary power supply fail or an internal fault be detected, the contact
gap 3-5 is opened.
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When a fault has been detected, the green READY LED indicator starts blinking, a
fault indication text is displayed on the HMI and an event “IRF activated” (E31) is
generated over serial communication.
4.1.11.2. Fault indication texts
Below, the different fault indication texts that may appear, the corresponding fault
codes and the actions that should be taken. The fault code is only used for remote
control systems connected to the serial communication.
IRFoutputr
ex
IRF IRF
5
4
3
5
4
3
Normal condition Fault condition
Table 4.1.11.2-1 Fault indications
Fault indication
Fault
code
Reason/Action
INTERNAL FAULT
Relay HSPO1 1 Protection operative, but the faulty output relay cannot be
controlled
INTERNAL FAULT
Relay PO1 7 Protection operative, but the faulty output relay cannot be
controlled
INTERNAL FAULT
Relay PO2 8 Protection operative, but the faulty output relay cannot be
controlled
INTERNAL FAULT
Relay PO3 9 Protection operative, but the faulty output relay cannot be
controlled